Haditha, Hamdaniyah, and Mahmudiya – Iraqi cities where US troops are alleged to have committed wartime atrocities – may not have seared the public consciousness as deeply as did My Lai in Vietnam. But the cases, including new criminal charges filed Thursday against eight marines in connection with the killing of 24 civilians in Haditha, are sure to focus more attention on how the military handles abuse and killing of prisoners and civilians.

The serious charges brought in these cases also raise basic questions about how the US military-justice system proceeds against alleged atrocities:

Prosecution in such cases falls under the US Uniform Code of Military Justice, the Law of Armed Conflict, and the Geneva Conventions. But it is the "rules of engagement" that may be most relevant for troops going into battle.

Such rules for combat typically are set by the unit commander just before an operation begins, based on an evaluation of mission, enemy, terrain, troops, and time available, says retired Army Col. Dan Smith, a military analyst with the Friends Committee on National Legislation, the Quaker lobby in Washington. But, he adds, rules of engagement "can be idiosyncratic."

Colonel Smith notes, too, that "soldiers always have the right of self-defense using even deadly force if they judge that they are in danger of suffering grievous wounds or death from enemy action."

In the Haditha case, those marines charged with killing civilians (including 10 women and children shot at close range) are expected to assert that they were fired on from houses near where their convoy was hit by an improvised explosive device (IED) that killed a lance corporal.

"Our view has been and continues to be that these are combat-related deaths," defense lawyer Gary Myers told the Associated Press. Mr. Myers represents Lance Cpl. Justin Sharratt, who faces one charge of murder involving unpremeditated killings of three men in a house.

Evidence gathered by military investigators contradicts that, prompting the Marine Corps to charge four of the eight marines with murder. It also led Thursday to charges against four others – unit officers not present at the scene – of failing to properly investigate and report the event. The highest-ranking officer to be charged is a lieutenant colonel, accused of failing to obey an order or regulation, encompassing dereliction of duty.

That raises questions about the responsibility of officers up the chain of command, from lieutenants leading platoons to colonels commanding brigades.

Rank should be important in assessing professional and perhaps even criminal responsibility, says Gary Solis, a 26-year Marine Corps veteran who served as a courts-martial prosecutor and judge.

"Under the law of armed conflict, if a superior knew, or should have known, of a subordinate's misconduct, and he took no action to stop it or to punish it, then he is himself personally criminally liable for the crime committed," says Dr. Solis, who directed the law of war program at West Point and now teaches at Georgetown Law School in Washington.

"That's basic World War II Nuremberg Tribunal stuff," he says. "But how often have we seen the principle honored? Not often."

During the nine-year Vietnam War, 95 soldiers and marines were convicted of murder or manslaughter of noncombatants. Courts-martial resulted in sentences as stiff as 50 years and life in prison.

In Iraq and Afghanistan, most incidents involving civilian deaths caused illegally by US forces have resulted in far lighter punishment, Solis finds.

For example, an Army chief warrant officer charged with negligent homicide in the 2003 death of an Iraqi detainee received a letter of reprimand, a fine of $6,000, and two months' restriction to Fort Carson, Colo. A sergeant involved in the beating death of an Afghan detainee in 2005 was reprimanded, given a one-grade demotion, and fined $1,000. In the Abu Ghraib prison scandal, the most senior officer punished was Army Reserve Brig. Gen. Janis Karpinski, demoted to colonel.

But dealing with detainees is very different from fighting in the heat and fog of battle, especially when the enemy emerges from or blends into the civilian populace. That situation, which troops face routinely in Iraq and Afghanistan, can lead to a difficult and potentially deadly paradox.

"Because Army personnel are trained for conventional warfare, they naturally want to kill the enemy," says national security analyst Ivan Eland of the Independent Institute, a nonpartisan think tank. "But in counterinsurgency warfare, a premium must be put on providing security for the population without killing civilians.

In Haditha, the death of one marine and injuries to two others while traveling in a convoy preceded the attacks on Iraqi civilians. The squad leader that day faces the most serious charges – murdering 12 people and ordering other marines to kill six people. His attorney said the charges carry a maximum penalty of life in prison.

Other recent cases of civilian deaths at the hands of US troops point to murderous intent.

In the Hamdaniyah case, seven marines and a Navy corpsman have been charged in the kidnap and murder of an Iraqi man, and then making it look as if he had planted an IED. So far, four have pleaded guilty to lesser charges in return for prison terms of less than two years.

In the Mahmudiya case, five Army soldiers have been charged in the rape and premeditated murder in April of a 14-year-old Iraqi girl and the murder of her parents and 5-year-old sister. One soldier pleaded guilty to avoid the death penalty. Another, a sergeant charged with dereliction of duty for failing to report the crimes, accepted an "other than honorable" discharge from the Army. Cases against the others are pending.

As with civilian trials, the nature of the evidence may lead military prosecutors to conclude that negligent homicide – not premeditated murder – is the most serious case they can make.

"Even with negligent homicide, the starched and pressed judge advocate who's not been in combat has to convince a jury that the young [marines] who daily risked their lives in Iraq are unworthy of belief," says Solis, the former Marine Corps judge advocate. "That could be a hard sell, and acquittals would not surprise me."

Some experts attribute such atrocities to the stress of enduring multiple tours of duty in Iraq, as well as the very difficult circumstances of fighting an unconventional war.

"It seems to me the main point is that these incidents are symptoms of combat stress," says John Pike, director of globalsecurity.org. "The question is whether the combat stress management system is doing a good job because there are so few incidents or a bad job because these incidents happened."